Spring Transition Dates and Fall Transition Dates

Graph of Spring Transition Dates and Fall Transition Dates various methods

OSCURS Method

Method & Data Reference

Ingraham, W.J., Jr. and R. K. Miyihara. 1988. Ocean surface current simulations in the North Pacific Ocean and Bering Sea (OSCURS-Numerical Model). NOAA Tech. Mem., NMFS F/ NWC-130, 155 p.

Summary

Each year, along the Pacific Coast of North American between San Francisco (38 North Latitude) and the Queen Charlotte Islands (52 North Latitude), the coastal winds switch from the southerly winds of winter to the northerly winds of summer producing a transition in wind called the spring transition. Conversely, the yearly switch back from the northerly winds of summer to the southerly winds of winter produce a fall transition. The summer winds, which occur after the spring transition and prior to the fall transition, are known to be favorable for upwelling -- a process that transports the nutrients to the ocean surface, feeding the near-shore food chain. Estimates of the transition dates were derived from smoothed synthetic winds computed by the ocean surface currents model OSCURS (Ingraham and Miyihara 1988), which used daily sea level atmospheric pressure fields for years 1946 to 1994 as input. The spring and fall transition dates were calculated for the latitude of the Columbia's mouth (46 deg 12' North Latitude).

Disclaimer

The dates of the spring and fall transitions contained on the web page should be considered provisional. They are values which are approximations to the true spring and fall transition dates. The estimates depend on the degree and type of smoothing used on the synthetic winds derived from OSCURS. Neither NOAA nor the University of Washington is responsible for any misuse of these data.

Logerwell et al. Method

Method Reference

Logerwell, E.A., N. Mantua, P. Lawson, R.C. Francis, V. Agostini. 2003. Tracking environmental processes in the coastal zone for understanding and predicting Oregon coho (Oncorhynchus kisutch) marine survival. Fisheries Oceanography 12:554-568.

Data Reference

E. Logerwell (pers. com. 2007)

Summary

The date of spring transition can be indexed in several ways; the Logerwell et al. (2003) method indexes the spring transition date based on the first day when the value of the 10-day running average for upwelling is positive and the 10-day running average for sea level is negative.

Disclaimer

Transitions dates contained on the web page should be considered provisional. They are values which are approximations to the true spring and fall transition dates. Neither NOAA nor the University of Washington is responsible for any misuse of these data.

Peterson Method

Update

19 August 2010. All spring and fall transition estimates for all years updated based on a re-run of the cluster analysis for the complete zooplankton data set.

Method Reference

Hooff, Rian C. and William T. Peterson. 2006. Recent increases in copepod biodiversity as an indicator of changes in ocean and climate conditions in the northern California current ecosystem. Limnol. Oceanogr. 51:2042-2051.

Keister, J.E. and W.T. Peterson. 2003. Zonal and seasonal variations in zooplankton community structure off the central Oregon coast, 1998-2000. Prog. Oceanogr. 57:341-361.

Peterson, W.T. and J.E.Keister. 2003. Interannual variability in copepod community composition at a coastal station in the northern California Current: a multivariate approach. Deep-Sea Res. 50:2499-2517.

Peterson, W.T. and F.B. Schwing. 2003. A new climate regime in Northeast Pacific ecosystems. Geophysical Research Letters. 30(17): OCE 6 1-4.

Peterson, W.T., Hooff, R.C., Morgan, C.A., Hunter, K.L., Casillas, E. and Ferguson, J.W. 2006. Ocean Conditions and Salmon Survival in the Northern California Current. White Paper, 52p.

Summary

The biological spring transition date is the day of a biweekly Newport Research Station research cruise at hydrographic baseline station NH 05 off Newport, Oregon when copepods sampled in plankton nets cluster out as a northern (cold-water) community (Peterson and Keister, 2003). This date is a useful indicator of salmonid feeding conditions because it marks the first appearance of the kind of food chain that coho and Chinook salmon seem to prefer, that is one dominated by large, lipid-rich copepods, euphausiids, and juvenile forage fish. Taken from: Peterson et al. (2006).

Similarly the biological fall transition date is the last time in a particular year when the "cold water copepods" were found in the plankton samples (William Peterson, pers. comm.).

The estimates of biological spring transition were developed and compiled by Dr. William T. Peterson.

Notes from Dr. William Peterson

Dates shift around with updates as the data are based on a hierarchical clustering of the entire copeopod data set (n = 440 samplings at the baseline station five miles off Newport, from 1969-present). Whenever new data are added to the data set, the clustering algorithm is re-run and dates will jump around between "winter" and "summer".

Why are the "biological" spring transition dates so different from the others? The answer is as follows: the physical spring transition means that winds have begun to blow from the north and the coastal currents have begun to flow to south (which is why sea level drops). Although this event marks the beginning of spring, there is a time lag after the physical transition before the spring zooplankton are advected into the area. This is an important consideration because the winter zooplankton, being sub-tropical species, are a poor quality food resource (they are small and have very low lipid content). The spring zooplankton on the other hand are "northern" species whose home is the coastal waters of the Gulf of Alaska; they are relatively large and lipid-rich thus have a high bioenergetic content. Since these animals are residents of waters well to the north of Oregon, it takes several weeks before they are advected south to waters off Central Oregon. Thus, the time lag between the beginning of upwelling and the appearance of zooplankton that contribute to high productivity.

Dr. William Peterson requests the data not be used for publication without his consent.

Dr. William T. Peterson
Fish Ecology Division
Northwest Fisheries Science Center
National Marine Fisheries Service
Newport Research Station
2032 S Marine Science Drive
Newport, Oregon 97365-5275
Phone: 541-867-0201
bill.peterson@noaa.gov

Pierce and Barth Method

Method Reference

Barth, J. A., B. A. Menge, J. Lubchenco, F. Chan, J. M. Bane, A. R. Kirincich, M. A. McManus, K. J. Nielsen, S. D. Pierce, and L. Washburn (2007) Delayed upwelling alters nearshore coastal ocean ecosystems in the northern California current, Proceedings of the National Academy of Sciences, 104, 3719-3724.

Gustafsson, F. (2000) Adaptive filtering and change detection, John Wiley.

Hinkley, D. and E. Schechtman (1987) Conditional bootstrap methods in the mean-shift model. Biometrika, 74, 85-93.

Huyer, A., E. J. C. Sobey, and R. L. Smith (1979) The spring transition in currents over the Oregon continental shelf. J. Geophys. Res., 84, 6995-7011.

Large, W. G. and S. Pond (1981) Open ocean momentum flux measurements in moderate-to-strong winds. J. Phys. Oc., 11, 324-336.

Page, E. S. (1954) Continuous inspection schemes. Biometrika, 41, 100-115.

Pierce, S. D., J. A. Barth, R. E. Thomas, and G. W. Fleischer (2006) Anomalously warm July 2005 in the northern California Current: historical context and the significance of cumulative wind stress, Geophys. Res. Letters, 33, L22S04, doi:10.1029/2006GL027149.

Summary from "Wind stress, cumulative wind stress, and spring transition dates: data products for Oregon upwelling-related research "

Alongshore wind stress cumulative from the spring transition represents energy input into the upwelling system over the course of each season. This has been found to be strongly correlated with a number of different upwelling metrics (Pierce et al., 2006), eg. NH-line surface-layer temperature (0-30m).

Wind stress here is derived from observed winds at Newport, Oregon, using the method of Large and Pond (1981). The hourly data are low-pass filtered to remove diurnal variations. The spring and fall transitions (Huyer et al., 1979) are estimated for each year from the alongshore wind stress record, using a CUSUM algorithm for change-point detection (Page, 1954; Gustafsson, 2000). The significance (95%) of these two mean-shift change-points within each year's time series is confirmed using bootstrapping, as suggested by Hinkley and Schechtman (1987).

We hope that researchers will find it useful to compare their own upwelling-related data to the general development of upwelling represented by this cumulative wind stress product. Plots and data are available: damp.coas.oregonstate.edu/windstress/.

S. D. Pierce and J. A. Barth, College of Earth, Ocean, & Atmospheric Sciences

Logerwell based CBR Method

Method Reference

Logerwell, E.A., N. Mantua, P. Lawson, R.C. Francis, V. Agostini. 2003. Tracking environmental processes in the coastal zone for understanding and predicting Oregon coho (Oncorhynchus kisutch) marine survival. Fisheries Oceanography 12:554-568.

Bilbao, P. 1999. Interannual and Interdecadal Variability in the Timing and Strength of the Spring Transitions along the United States West Coast. M.S. Thesis. Oregon State University, Oceanography.

Summary

The method is the same as that used in Logerwell (2003) to estimate spring transition dates.

Two time series were inspected for seasonal transitions: (1) area averaged daily upwelling indices for 42º to 48ºN, 125ºW (http://www.pfeg.noaa.gov), and (2) daily sea level residuals (corrected for the inverse barometer effect) measured at Neah Bay, WA, 48º22.1'N,124º37.0'W (University of Hawaii Sea Level Center, http://uhslc.soest.hawaii.edu/). High frequency variation was filtered out by applying a low pass filter with a stop frequency of 1/(10 days) (S-PLUS, MathSoft, Inc., Seattle, WA, USA). To extract the seasonal pattern, a low pass filter with a stop frequency of 1/(90 days) was constructed. The date of fall transition was chosen as the date when the 1/(10 days) low pass filtered lines crossed zero.  The 1/(90 days) low pass filter line confirmed that the selected date marked the beginning of a new seasonal state.

In most years the time series agree and the date is easy to pick. In other years the signals do not point to a single transition and some judgment must be made. Thus, although the model allows selection of the date, it does not form a completely objective and automated system for choosing that date.

Update

13 April 2007. Estimates for 1997, 2000, and 2004 were updated.

Disclaimer

Transitions dates contained on the web page should be considered provisional. They are values which are approximations to the true spring and fall transition dates. The University of Washington is not responsible for any misuse of these data.

CBR Mean Method

Method & Data Reference

Mean Spring and Fall Upwelling Transition Dates off the Oregon and Washington Coasts. 2007. Van Holmes, Chris. white paper.

Summary

Pacific Fisheries Environmental Laboratory publishes indices of the intensity of large-scale, wind-induced coastal upwelling and alongshore transport at standard locations on a monthly basis. The CBR Mean method uses data from 1967 to the present for three locations along the Pacific Northwest coast:

  1. 42N125W West of OR/CA border,
  2. 45N125W West of Siletz Bay Lincoln, OR,
  3. 48N125W West of La Push, WA.

For all years, the CBR Mean method takes each day's upwelling deviations from the site-specific mean offshore transport. The upwelling deviation was used to account for long term trends at each site. Then the daily deviations were averaged from the three sites. The average upwelling deviation indices are then smoothed using a 15 day central mean calculation. The use of a central mean avoids the trailing nature of a running mean. The smoothed cumulative upwelling deviation indices are then examined for spring minima and fall maxima through the entire series. The julian day of these extremes are listed as the CBR Mean Spring and Fall Transition Dates.

Disclaimer

The dates of the spring and fall transitions contained on the web page should be considered provisional. They are values which are approximations to the true spring and fall transition dates. The University of Washington is not responsible for any misuse of these data.

Further Investigation

DART Pacific Ocean Coastal Upwelling Index Graphics & Text queries, data courtesy of NMFS Pacific Fisheries Environmental Laboratory

Northwest Fisheries Science Center, NOAA

Data

Year Spring Transition Dates Fall Transition Dates
OSCURS Logerwell et al. Peterson Pierce and Barth CBR Mean OSCURS Logerwell based CBR Peterson Pierce and Barth CBR Mean
Year Spring Transition Dates Fall Transition Dates
OSCURS Logerwell et al. Peterson Pierce and Barth CBR Mean OSCURS Logerwell based CBR Peterson Pierce and Barth CBR Mean
2016 87 81 273 278
2015 92 101 46 278 293
2014 101 161 130 94 268 263 281
2013 100 91 97 96 269 234 261
2012 121 125 125 114 299 281 284
2011 100 82 106 90 272 254 260
2010 100 169 161 99 328 257 286
2009 85 65 134 67 335 284 279
2008 89 64 120 36 301 259 297
2007 74 81 117 71 270 365 271 308
2006 112 180 110 108 304 304 304 304
2005 145 238 142 106 272 271 272 284
2004 110 132 112 89 311 288 234 338
2003 112 156 110 105 288 276 269 278
2002 80 108 107 81 310 305 308 302
2001 61 79 121 64 316 311 280 296
2000 72 97 164 78 294 297 285 288
1999 91 134 89 88 310 308 292 294
1998 105 263 83 71 310 267 258 277
1997 146 135 126 78 256 239 228 255
1996 120 185 117 116 321 305 275 311
1995 95 NA 110 100 311 NA 264 309
199493.23119 87 NA 115 82 286.9727 298 NA 286 294
1993130.7614 161 NA 162 116 298.7134 325 NA 278 327
199269.20528 123 NA 121 64 281.1374 292 NA 289 289
199171.92012 99 NA 128 62 297.9998 309 NA 294 304
199083.04251 81 NA 81 76 281.5938 294 NA 275 289
198999.03588 97 NA 96 94 284.9838 293 NA 266 288
198888.55508 68 NA 155 85 289.755 305 NA 268 301
1987101.2242 81 NA 106 72 297.4697 312 NA 309 309
198694.79562 89 NA 85 86 280.8877 280 NA 255 292
198570.7562 48 NA 158 45 279.6091 292 NA 283 290
1984107.5674 112 NA 109 272.4462 277 NA 276
198395.21371 126 202 91 289.6044 285 231 288
198283.30457 109 NA 104 272.6492 261 NA 276
198194.60262 88 NA 83 268.9149 263 NA 262
1980109.4162 78 NA 76 275.2528 291 NA 295
197974.41698 73 NA 65 272.4335 286 NA 289
197885.18182 97 NA 66 302.4553 280 NA 317
197771.79939 74 NA 70 274.1748 295 NA 292
197684.66428 103 NA 100 293.4859 292 NA 296
197573.96655 83 NA 80 273.5765 276 NA 273
1974102.7074 102 NA 98 297.0226 309 NA 306
197374.19205 80 NA 64 285.4921 292 NA 287
1972103.103 107 NA 102 300.853 306 NA 304
1971102.2719 106 79 103 292.8313 312 310 290
197068.57823 78 79 74 270.8927 290 293 287
196978.03237 117 116 268.9529 260 258
196890.6561 84 272.0233 282
196759.49914 82 268.3312 271
196688.50795 281.4956
196544.54589 277.2084
196441.98558 275.7526
196371.96294 256.3281
196251.33193 272.6711
196191.95937 307.0709
1960141.8394 285.5177
195984.73013 292.2119
195899.23275 268.9639
195790.8761 279.7934
195682.69133 282.0516
195564.76729 283.2569
195464.54433 265.5847
195351.18787 269.0659
195269.06229 278.7719
195164.79611 271.8619
1950109.9127 269.7495
1949115.0458 291.0623
1948139.7 256.3207
1947102.9139 270.5
1946106.5074 259.1